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In this paper, we study a special class of quasi-homomorphisms, i.e. quasi-retractions from a group to its subgroups. We first give some algebraic and geometric properties of quasi-retracts and then propose a theory of quasi-split short…

Group Theory · Mathematics 2025-08-21 Renxing Wan

Distance-regular graphs have many beautiful combinatorial properties. Distance-transitive graphs have very strong symmetries, and they are distance-regular, i.e. distance-transitivity implies distance-regularity. In this paper, we give…

Combinatorics · Mathematics 2018-10-23 Hui Zhou , Cheryl Praeger , Michael Giudici , Rongquan Feng , Xingui Fang

The emergence of massive graph data sets requires fast mining algorithms. Centrality measures to identify important vertices belong to the most popular analysis methods in graph mining. A measure that is gaining attention is forest…

Data Structures and Algorithms · Computer Science 2021-01-18 Alexander van der Grinten , Eugenio Angriman , Maria Predari , Henning Meyerhenke

Statistical analysis of large and sparse graphs is a challenging problem in data science due to the high dimensionality and nonlinearity of the problem. This paper presents a fast and scalable algorithm for partitioning such graphs into…

Data Structures and Algorithms · Computer Science 2018-12-24 Hannu Reittu , Lasse Leskelä , Tomi Räty , Marco Fiorucci

Square contingency tables are traditionally analyzed with a focus on the symmetric structure of the corresponding probability tables. We view probability tables as elements of a simplex equipped with the Aitchison geometry. This perspective…

Statistics Theory · Mathematics 2025-06-04 Keita Nakamura , Tomoyuki Nakagawa , Kouji Tahata

A graph $X$ is said to be {\it distance--balanced} if for any edge $uv$ of $X$, the number of vertices closer to $u$ than to $v$ is equal to the number of vertices closer to $v$ than to $u$. A graph $X$ is said to be {\it strongly…

Combinatorics · Mathematics 2007-05-23 K. Kutnar , A. Malnic , D. Marusic , S. Miklavic

We refine the construction of quasi-homomorphisms on mapping class groups. It is useful to know that there are unbounded quasi-homomorphisms which are bounded when restricted to particular subgroups since then one deduces that the mapping…

Group Theory · Mathematics 2007-05-23 Mladen Bestvina , Koji Fujiwara

The \emph{distance-number} of a graph $G$ is the minimum number of distinct edge-lengths over all straight-line drawings of $G$ in the plane. This definition generalises many well-known concepts in combinatorial geometry. We consider the…

Combinatorics · Mathematics 2008-09-09 Paz Carmi , Vida Dujmović , Pat Morin , David R. Wood

It is well-known that quasi-isometries between R-trees induce power quasi-symmetric homeomorphisms between their ultrametric end spaces. This paper investigates power quasi-symmetric homeomorphisms between bounded, complete, uniformly…

Metric Geometry · Mathematics 2012-06-12 Bruce Hughes , Álvaro Martínez-Pérez , Manuel A. Morón

The central theorem of topological graph theory states that the graph minor relation is a well-quasi-order on graphs. It has far-reaching consequences, in particular in the study of graph structures and the design of (parameterized)…

Computational Geometry · Computer Science 2025-12-04 Corentin Lunel , Clément Maria

We solve the subgraph isomorphism problem in planar graphs in linear time, for any pattern of constant size. Our results are based on a technique of partitioning the planar graph into pieces of small tree-width, and applying dynamic…

Data Structures and Algorithms · Computer Science 2007-05-23 David Eppstein

A well-quasi-order is an order which contains no infinite decreasing sequence and no infinite collection of incomparable elements. In this paper, we consider graph classes defined by excluding one graph as contraction. More precisely, we…

Combinatorics · Mathematics 2016-12-20 Marcin Kamiński , Jean-Florent Raymond , Théophile Trunck

In this paper we systematically study various properties of the distance graph in ${\Bbb F}_q^d$, the $d$-dimensional vector space over the finite field ${\Bbb F}_q$ with $q$ elements. In the process we compute the diameter of distance…

Combinatorics · Mathematics 2008-04-21 Derrick Hart , Alex Iosevich , Doowon Koh , Steve Senger , Ignacio Uriarte-Tuero

Beyond-planarity focuses on combinatorial properties of classes of non-planar graphs that allow for representations satisfying certain local geometric or topological constraints on their edge crossings. Beside the study of a specific graph…

Data Structures and Algorithms · Computer Science 2019-08-27 Patrizio Angelini , Michael A. Bekos , Michael Kaufmann , Thomas Schneck

We say A is a quasi-normal subgroup of the group G if the commensurator of A in G is all of G. We develop geometric versions of commensurators in finitely generated groups. In particular, g is an element of the commensurator of A in G iff…

Group Theory · Mathematics 2009-12-31 Gregory R. Conner , Michael L. Mihalik

We introduce the notion of coarse bottlenecking in graphs and coarse skeletons of graphs and show how bottlenecking guarantees that a skeleton resembles (up to quasi-isometry) the original graph. We show how these tools can be used to…

Metric Geometry · Mathematics 2024-10-23 Michael Bruner , Atish Mitra , Heidi Steiger

Graph-based clustering methods like spectral clustering and SpectralNet are very efficient in detecting clusters of non-convex shapes. Unlike the popular $k$-means, graph-based clustering methods do not assume that each cluster has a single…

Machine Learning · Computer Science 2023-02-28 Mashaan Alshammari , John Stavrakakis , Masahiro Takatsuka

We study the large scale geometry of mapping class groups MCG(S), using hyperbolicity properties of curve complexes. We show that any self quasi-isometry of MCG(S) (outside a few sporadic cases) is a bounded distance away from a…

Geometric Topology · Mathematics 2010-04-12 Jason Behrstock , Bruce Kleiner , Yair Minsky , Lee Mosher

Let G be a simple, connected graph on n vertices. Let d_G(u,v) denote the distance between vertices u and v in G. A subgraph H of G is isometric if d_H(u,v)=d_G(u,v) for every u,v in V(H). We say that G is a distance-preserving graph if G…

Combinatorics · Mathematics 2014-05-08 Abdol-Hossein Esfahanian , Ronald Nussbaum , Dennis Ross , Bruce E. Sagan

We develop a new framework for generalizing approximation algorithms from the structural graph algorithm literature so that they apply to graphs somewhat close to that class (a scenario we expect is common when working with real-world…